This invention relates to electrostatic precipitators or filters by means of which dust particles are removed from an air stream. In particular, this invention relates to a method for operationally ascertaining the existence of an optimal interval or period for rapping the electrodes of such a precipitator.
In one kind of conventional electrostatic precipitator, dust or particle charged air flows between collector plates which are electrically coupled to one another. The voltage across the collector plates causes the solid particles suspended in the air flowing between the plates to move towards one or the other of the electrodes and to become deposited thereon. The electrodes are periodically cleaned of the resulting dust layers by means of a mechanical knocking or rapping operation. If, on the one hand, the rapping occurs too infrequently, the size of the dust layers on the collector electrodes may periodically become so large as to cause a distinct reduction in the performance of the precipitator. If, on the other hand, the rapping occurs too frequently, the mean dust content of the air at the output of the precipitator may undergo a substantial and undesirable increase. From these facts it might be assumed that there is a rapping interval at which the mean dust content of the outflowing air is a minimum. However, investigations and calculations show that this is not always the case, i.e., that there are types of dust for which actual optimal rapping periods do not exist. For both analytic and iterative methods of computation it is important to known whether there is, for a given type of dust, an optimal rapping period or interval, i.e., a rapping interval resulting in a mimimal mean dust content of the air at the output of the precipitator.
An object of the present invention is to provide a method for operationally determining the existence of an optimal rapping interval for the electrodes of an electrostatic precipitator.
Another object of the present invention is to provide such a method by means of which an optimal rapping interval may be calculated from operationally determined parameters.